Polymerization of butadiene hydrocarbons



Patented July 3l, 19,45y

' I Poorten or som-sommi msocmsoss i George L. Bros, Jr., s. u en,

by means n, Ghia, asaign'or, to The B. F. Goodrich Company, n, h10, a corporation'of New 'York No Drawing. specimen om is, mi,

. mamme l es. ,wieso-SM) This invention-relates to the polymerization ci butadiene-1,3 hydrocarbons, and f particularly vto a method whereby butadiene-1.3 hydrocarbons may be polymerized in the form o! aqueous emulsions to form products closely resembling natural crude rubber. f

The emulsion 'polymerization oi butadiene-1,3 hydrocarbons either alone or in admixture with other monomers copolymerizable therewith to.

form compositions ci matter more or less resembling rubber is well known. It has been commonly observed, however, that the products oi such polymerizaticn reactions often resemble vulcanized ruhmr rather than natural crude rubber in respect to solubility. plasticity, and processing characteristics. Thus it has-citen been found that the polymers were insoluble in, and; in some cases, not even swelled by benzene or acetone, and that they were tough, non-plastic materials which either would not homogenizel on a mill or which were very dimcult to mill and to subject to, other ordinary processing operations. f

l have now discovered a class oi materials which modifies the emulsion polymerization of butadiene-1,3 hydrocarbons in such a manner that polymers more nearly resembling natural crude rubber may be produced than when the polymerization is eeeted in the ece of the materials of this invention. Thezclass of materials,

' which I have termed modiers consistsof compounds containing the group ni-x-c-s-o-ni wherein R1 is an organic radical derived by reoml .presence of an organic'sclvent such as acetone..

in which case the reaction occurs as soon as the acetone solution of the reactionsl are admixed as vevidenced bythe precipitate of sodium chloride. The reaction between the xanthate and the acid chloride may also be eidected in an aqueous mee,

dium if the acid chloride isv sumciently stable in water.

The xenthates employed in this reaction may 0 be prepared by the hnown reaction with carbon disulfide and. en alkali such as sodium hydroxide of an alcohol auch as methylalcohol, ethyl slcchol, isopropyl alcohol, ten-butyl alcohol, act.

i amyl alcohol, lauryl alcohol, benzyl alcohol,

cyclohexyl alcohol, tetrahydroiururyl alcohol, allyl alcohol, methoxyethyl alcohol, or one of the corresponding thiols. Although any acid chlorides or bromides such as acetyl chloride, acetyl bromide, butyryl chloride, or caproyl chloride, maybe employed, the aroyl chlorides `such as .benaoylA chloride, benzoyl bromide, naphthoyl \chloride, toluyl chloride, etc., are the preferred reactants. i

The edect of the modiers oi! this invention on emulsion polymerization is shown by the copolymerizatlcn at C. of 55 parts by weight of butadiene and 45 parte of acrylonitrile in the presence oli-about 250 parts of s. 2% aqueous solution of myristic scid which had been 85% neu- 30 tralized with sodium hydroxide, 0.35 part ci hyadrogen peroxide as an initiator, 0.11 part of sodium ferri pyrophosphste as an activator. and 1.0 part of isopropoxythiono benzoyl monosuiiide. The polymerobtained by coagulating the latex 5- Iormed was in a plastic and coherent iorm and was #7% soluble in acetone, while the polymer v obtained by polymerization in the absence of any modifier was in the form of a non-coherent crumbs which were practically insoluble in ace` 40 tone. The vulcanizate prepared by testing the.V

.modiiler in o. tire tread' recipe was unusually strong and exhibited a .high elongation.

The proportion` in which themodier is included in the composition depends somewhat upon the properties desired in the' product, the higher proportions ol modiiier in leneral producing softer, more' soluble polymersqvvery' small .amounts oi modiner such as 0.1% or even less y based on themonomers in the emulsion moy nrorouneiy meer un nature or the polymer produced,

and amountsl up to 5% or more may advantabe employed. It may also be' advantageous to employ a mixture of one ci the modi- A .i fiers herein claimed with other known types ot. mrecuonmayeonvenisuybe remaining sa mdlerswhwtetrslhlthiurempolwmw..

l ethers, and ketones.

mercaptoalkylthiazoles or other types of compounds known to exhibit modifying activity in emulsion polymerization processes.

The modifying agentsoi' this invention may be employed in the polymerization in the form of an aqueous emulsion oi' butadiene-1,3 hydrocarbons, by which is meant butadiene-1,3 (commonly called butadiene) and its Ahomologues which f enter into polymerization reactions in essentially the same manner, either alone or in admixture with each other and/or other monomers copolymerizable therewith such as styrene, isobutylene,

I claim:

l. The method which comprises'polymerizlng a. butadiene-1,3 hydrocarbon in an aqueous emulsion in the presence of an alkoxythiono benzoyl monosulde.

2. The method which comprises polymerizing a butadiene-1,3 hydrocarbon in an aqueous emulsion in the presence of isopropoxythlono benzoyl monosulide.

, 3; The method which comprises polymerizing in aqueous emulsion a. mixture of butadiene-1,3

acrylonitrile, methyl methacrylate, methyl acrylate, methyl vinyl ether, methyl isopropenyl ketone, and other unsaturated hydrocarbons, esters,

For the production oi ruhbery products, these other monomers should he employed in an amount smaller than the butadiene.

The polymerization of the alcove materials in aqueous emulsion may be eectsd'by various ini tiators of polymerization such as per-compounds including per-acids, peroxides, and per-salts such as persulfates, perhorates, percarhonates, and the like as well as other types of initiators such as diazoaminobenzene, hydrosultes, bisulfites, and

dipotassium diazomethane disulfonate.

The polymerization reactions may he catalyzed in any desired manner, the use oi heavy metal catalysts being particularly desirable. The heavy metal catalyst may he added to 'the-emulsion in the form of less than 0.1% based on the weight and a monomer copolymerizable therewith in aqueous emulsion, inthe presence oi an alkoxy thiono benzoyl monosulilde.

4. The method which comprises polymerizing in aqueous emulsion a mixture of butadiene-1,3

of the monomers oi a simple ioniaalole heavy v metal salt such as cobalt chloride, niclseious sulfate,- mercuric chloride, etc., as disclosed in the copending application oi William D. Stewart,-

Serial No. 379,712. filed February 14, wel, or in the form of a redox system comprising a heavy metal and a material such as sodium pyrophosphate, levulinic acid, glycine, cystine, hete-mercaptoethanol, quebrachitoi, ox-bile or' cholesterol as disclosed in the copending applications of William D. Stewart, Serial Nos. M9313 to 379,717 med February 14, 1941.

-Any of the ordinary emulsifying agents auch as' fatty acid soaps including sodium oleate, potassium steal-ate, sodium myristate, etc., maybe' terials such as hymolal suliates and alkaryl sulionates including sodium lauryl sulfate and sodium isopropyl naphthalene sulfonate.

Although I have herein disclosed specic emhodiments of my invention, i do not intend' to limit the invention solely thereto, for it. will be obvious to those. skilled in the art that many variations and modifications are within the spirit and scope of the invention as defined in'the appended claims.

.,employed, aswell as synthetic saponaceous mawherein R1 is an organic radical derived hy removing the hydroxyl group from a -monohydric alcohoLRz is an organic radical derived by removing the carboxyl ,group from a mono-carboxylic acid and X is a member of the class consisting of oxygen and sulfur.

El. The method which comprises polymerizing in aqueous emulsion a mixture of a butadiene-1,3 hydrocarbon and a monomer copolymerizable therewith in aqueous emulsion, in the presence oi a small amount of a compound o! theiorniula wherein R1 is an organic radical derived by refm'oving the hydroxyl group .from a'monohydric alcohohR2 is an organic radical derived'by removing the carboxyl group from a mono-car- .hoxylic acid and X is a member o! the class consisting of omen and sulfur. l l

` GEORGE L. axioma, Jn. 

